import React, { Component } from 'react'
class MyButton extends Component {
  render () {
    return (
      <button>按钮- { this.props.theme}</button>
    )
  }
}
class ToolBar extends Component {
  render () {
    return (
      <MyButton theme = { this.props.theme }></MyButton>
    )
  }
}
export default class App extends Component {
  render() {
    return (
      <div>
        <ToolBar theme = "dark" />
      </div>
    )
  }
}
 